Cardboard Promotions Big Sports Card & Memorabilia Show, Saturday, April 20, 11 to 7:30 and Sunday, April 21, 11 to 6, buy-sell-trade old & new sports cards & memorabilia, graded & ungraded cards, autographs & Pokemon cards, over 85 Vendor tables, free admission Free Autograph guests April 20: former Red Sox Bob Montgomery, 4 time Boston Marathon Champ Bill Rodgers, former Patriot Roland James. Autograph Guests April 21: Celtics 2 time Champ Don Chaney, Basketball Hall of Famer Tom ‘Satch’ Sanders and Red So 1967 Cy Young winner Jim Lonborg